With fast development of smartphones and a mobile Internet, a terminal device (for example, a camcorder or a camera), as an interface for connecting a real world and a virtual network world, has become a very important component in a smartphone. Every day, thousands of people use photo shooting functions or photographing functions of smartphones to record new things related or unrelated to the people.
In large quantities of new things recorded by people, there are a relatively large proportion of facial images. However, in a process in which a terminal device converts facial features into a facial image by using principles of optics, an optical distortion easily occurs, causing a distortion of facial features in the obtained facial image. For example, a barrel distortion occurs, that is, in an actual application, if a terminal device uses a pantoscopic lens for capturing an image, a barrel distortion occurs in facial features in the captured image; or a pincushion distortion occurs, that is, in an actual application, if a terminal device uses a long-focus lens for capturing an image, a pincushion distortion occurs in facial features in the captured image. In other words, severity of a facial distortion affects quality of a facial image.